


Defusing the Ice Man

by 24kitkat



Category: Sherlock (TV)
Genre: 221B Baker Street, 221b, BBC, F/M, M/M, OC, Siblings
Language: English
Status: In-Progress
Published: 2020-03-26
Updated: 2020-03-26
Packaged: 2021-03-01 05:08:12
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 825
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23329741
Author URL: https://archiveofourown.org/users/24kitkat/pseuds/24kitkat
Summary: Katherine Watson is John's younger sister. She is one of the few people that Sherlock regards as slightly more relevant than everyone else, but he isn't the only Holmes she has an effect on...
Relationships: Mycroft Holmes/Katherine Watson, Sherlock Holmes/John Watson
Comments: 8
Kudos: 28





	Defusing the Ice Man

**Summary for the Chapter:**

> Katherine Watson's introduction to Mycroft Holmes, though according to her, it isn't their first meeting.

John and Katherine stumbled into the apartment in fits of laughter. They continued to giggle and utter incomprehensible jokes to each other that only induced more hilarity into whatever had caused their outburst in the first place. They both glanced up with tears in their eyes and Katherine stopped short as she noticed someone sat facing Sherlock who was sprawled in his usual seat. John’s laughter eventually faded, and Katherine noticed him cough and stand ever so slightly in front of her as he too noticed the stranger in their apartment. He was yet to take a liking to Mycroft and their encounters thus far had not done much in the elder Holmes’ favour.  
John opened his mouth to speak, but Sherlock got there first.  
“My brother has a habit of inviting himself places. Therefore, I was not expecting him.”  
“I doubt you would have told us anyway if you were,” Katherine smirked knowingly, visibly relaxing as she saw Sherlock had the situation under control. Sherlock returned her expression with a small grin of his own. Despite not particularly liking humans in general, Sherlock had quickly decided upon first meeting Katherine that Watsons were an exception to this; they were not as ordinary or infuriating as most people.  
Mycroft finally turned himself properly to address the two by the door. Katherine blinked in sudden realisation obviously enough for Sherlock to raise an eyebrow at her in enquiry, however, she either didn’t notice or simply ignored this, likely the latter.  
“John, how nice to see you again,” he drawled with no real sincerity behind his greeting. John just inclined his head in acknowledgement. “I see you’ve brought along…” he paused as his eyes scanned over Katherine rapidly, provoking John to stand further in front of her with a hard glare at Mycroft. “…your sister? Pleased to meet you, Miss Watson.”  
He noticed with slight disappointment that she did not react to his slick deduction, though, admittedly, it was quite elementary. She had seen it all from Sherlock before, and she had quickly decided she wasn’t going to give this man the satisfaction of impressing her.  
“We have met actually, Mr Holmes, but you clearly don’t remember,” she scoffed, huffily. Mycroft raised his eyebrows; she’d successfully caught him off guard twice in one sentence: he was rarely called out for his mistakes, usually because he made so few, and he hardly ever forgot things – not the important ones anyway. He swiftly concluded that this woman had been of no real significance to him on whatever other occasion they had met and was just about to brush it off when yet another remark from the woman shocked him.  
It was hard to hear, as she muttered it, but it sounded an awful lot like: “Ungrateful snob…” and from Sherlock’s amused snort, he decided it had been exactly that. He stood up abruptly, doing his best to keep his anger unseen, but the smirk on Katherine’s face told him he had failed. He took a step forward, but quickly stopped as she did the same, stepping away from her protective brother.  
“I saved your life actually,” she stated matter-of-factly. Mycroft raised a stern eyebrow indicating that he still had no idea who she was. “I was an agent for the MI5 when they were jeopardised. The corruptors ordered me to assassinate you, but clearly I didn’t. I knew something was up – why on earth would the government want to kill off the human version of itself?”  
“Hang on a minute,” John interjected. “You’re telling me that Britain’s Secret Service, supposedly the safest and most tight-fast agency in the world, was jeopardised?”  
Mycroft glared down at Katherine. “That is confidential information,” he said through gritted teeth. “You could be killed for that.”  
He blinked in annoyance as the woman before him merely shrugged. “I’d like to see you try.”  
Sherlock beamed as he watched his brother stunned into silence for what must have been the tenth time in the last five minutes.  
“I think you probably owe Katherine a thank you then, by the sounds of it, Mycroft,” he piped up, grinning. Mycroft turned to glare at his cheeky younger brother, but before he could say anything, Katherine had interrupted him yet again.  
“Oh, don’t worry, Sherlock,” she smiled. “I doubt we’ll get one out of him anytime soon. I need to be off anyway. I’ll see you all around.”  
She gave Sherlock a small wave, patted Mycroft’s arm and gave John as swift hug as she walked out. Mycroft watched her go and realised that he hadn’t flinched away when she touched his arm like he usually does with any human contact. Sherlock had been watching Mycroft carefully and noticed him start slightly as he spoke.  
“You like her then, do you, brother?”  
Mycroft frowned, but before he had a chance to reply, John had loudly drawn his attention and greeted him with a furious glare.  
“He’d better not!”

**Notes for the Chapter:**

> This is (for now) the first part of my series with Mycroft Holmes and Katherine Watson. I will probably add a part (or parts) to come before this and there will be many more following it.


End file.
